The frequent allegation that the selective processes in the human species are no longer 'natural' is due to persistence of the obsolete nineteenth-century concept of 'natural' selection. The error of this view is made clear when we ask its proponents such questions as, why should the 'surviving fittest' be able to withstand cold and inclement weather without the benefit of fire and clothing? Is it not ludicrous to expect selection to make us good at defending ourselves against wild beasts when wild beasts are getting to be so rare that it is a privilege to see one outside of a zoo? Is it necessary to eliminate everyone who has poor teeth when our dentists stand ready to provide us with artificial ones? Is it a great virtue to be able to endure pain when anaesthetics are available?[Co-author with American statistician Gordon Allen]

We all felt the majesty of the body. In a very short period of time we had seen something that was bigger than each of us. A lot of people, even those who were not religious, were reverent and attributed the success to God. As we saw the artificial heart beat in Dr. Clark, the feeling was not aren't we great, but aren't we small.[Comment after surgery for the world's first human implant of a total artificial heart in the chest of dentist Dr. Barney Clark ]

In science it often happens that scientists say, 'You know that's a really good argument; my position is mistaken,' and then they would actually change their minds and you never hear that old view from them again. They really do it. It doesn't happen as often as it should, because scientists are human and change is sometimes painful. But it happens every day. I cannot recall the last time something like that happened in politics or religion.
(1987) -- Carl Sagan